Why Soybeans Planted Before Mother’s Day Might Be Struggling

Soybeans in many fields are struggling and growing slow. The majority of fields that are struggling were planted prior to the Mother’s Day weekend (the week prior to May 11th). Here are some of the other observations seen:

• There are differences between genetics. Some genetics handle “wet feet” better than other genetics. It is not just tolerance to Phytophthora that determines a varieties water tolerance, but how it can handle anaerobic conditions.

• Well drained fields look much healthier than poorly drained fields. In addition, well drained fields are better nodulated than poorly drained fields.

• Some varieties are showing symptoms of Fusarium or Rhizoctonia, which can sometimes be seen as a reddish-brown lesion at the soil line. According to the Compendium of Soybean Diseases regarding Fusarium, “When the disease is severe, seedling emergence is slow and poor and affected seedlings are stunted and weak.” Regarding Rhizoctonia, “Infected plants are stunted and yellow and have poor root systems because lateral roots often decay, leaving only the taproot and secondary roots.”Some genetics are showing this more than others.The picture below is more than likely Fusarium.

• Septoria Brown Spot is showing up on older leaves. Symptoms will include unifoliate leaves getting irregular brown spots, turning yellow, and falling off. Trifoliate leaves will have the brown spots, but not necessarily turn yellow (as the plant below shows). Normally this disease is not a big issue, but I have seen some varieties being susceptible and moving up the plant. If we continue to stay wet then these susceptible varieties may prematurely drop leaves and reduce yield.You may want to consider a fungicide for those susceptible varieties.